1. Field of the Invention
This invention relates to articulated fluid transferring apparatus, and more particularly, to an improved offshore loading system having an improved articulated loading arm.
2. Description of the Prior Art
The production of oil and gas from offshore wells has developed into a major endeavor of the petroleum industry, and this growth has led to the development of means for transporting petroleum products from offshore wells to shore-based refineries or storage facilities. Many of the wells are being drilled and completed in deep-water locations where the use of marine tankers of very large capacity constitutes the most practical and efficient method of transporting the petroleum products.
Some of the prior art loading facilities include a fluid handling means such as a fixed mooring buoy or an articulated loading column to which a tanker may be moored while loading. The tanker and the loading column move relative to each other during the loading operation due to winds, tides and the amount of fluid which is loaded into the tanker. The height of the tanker above the waterline changes as the tanker is loaded or unloaded, thus requiring that a flexible or articulated hose be connected between the tanker and the loading columm. When flexible hoses are used a tender is normally required to assist the tanker in picking up the flexible hoses for connection to the tanker's manifold. Such an arrangement not only requires the use of a tender, but movement of the tanker may cause the flexible hoses to be broken. The hoses are bulky, heavy, hard to handle and require a relatively large crew of workers to connect the hoses to the tanker. The hoses are also subject to wear and deterioration, can cause pollution due to rupture caused by sudden changes in fluid pressure and must be replaced frequently. Sudden changes in pressure can rupture or otherwise damage flexible hoses, thus requiring a relatively long sequence for connecting or disconnecting a hose to a tanker and for changing the rate of moving liquid through the hose between "full flow" rate and a "no fluid" rate. This may cause damage to the hose when a sudden disconnect of the hose is required due to an unexpected storm or to other emergency factors.
Some of the other prior art loading facilities include a marine loading arm having complex articulated arms that are heavy, bulky, and relatively expensive, and that require complex balancing systems, as balance of these arms change as the fluid content of the arm changes. When these arms are mounted on the loading column, power to operate the loading arm is provided on the loading column. The installation of the power system on these loading columns is expensive and maintenance is inconvenient and expensive. What is needed is a lightweight, simple, passive loading system which can be connected to a source of power on a marine tanker being loaded from the loading tower.